1. Field of the Invention
This invention relates to a fuel having reduced tendency to particulate dissemination under shock comprising a liquid hydrocarbon jet aviation fuel of flash point at least 90.degree. F. (32.2.degree. C.) containing dissolved atactic polypropylene.
2. Description of the Prior Art
It is known that when liquid hydrocarbon jet aviation fuels are subjected to conditions of shock, for example, in a crash of a jet aircraft with subsequent rupture of its fuel tanks, the fuel has a tendency to particulate dissemination into mists which can be readily ignited by flames, electric sparks, hot metal, etc., resulting in major hazard to all personnel in the immediate area.
Many efforts have been made in the past to reduce such hazard by incorporating in the fuel additives that have a tendency to reduce particulate dissemination. Thus, in U.S. Pat. No. 3,996,023 to Osmond et al (I), the additives employed are non-crystalline polymers devoid of polar groups, such as polymers derived from ethylenically unsaturated hydrocarbons, including isobutylene, butadiene, isoprene, mixtures of ethylene and propylene containing from 10 to 80 weight percent propylene, preferably from 18 to 25 weight percent of propylene, and alkylated polystyrenes. In U.S. Pat. No. 3,998,605 Osmond et al (II) empoys as additive a copolymer of ethylene with a higher olefin, preferably propylene, which contains not more than 95 percent, preferably not more than 85 percent, by weight of ethylene and has a molecular structure comprising at least two, preferably at least 10, runs of at least 10, preferably at least 20, units of ethylene separated by runs of hydrocarbon-soluble polymer which may be a random copolymer of ethylene and higher olefin or a homopolymer of the higher olefin. In U.S. Pat. No. 4,002,426 Osmond et al (III) have found that additives similar to those defined in their U.S. Pat. No. 3,996,023, referred to above, can also be used but wherein the polymers contain polar groups which form inter-molecular associative bonds with each other when the liquid is subjected to shear, such as nitrile, nitro, sulfone, aromatic residues substituted with these groups and ion pairs.